The modern golf ball may be constructed in a number of ways. By altering ball construction and composition, manufacturers can vary a wide range of playing characteristics, such as resilience, durability, spin, and “feel,” each of which can be optimized for various playing abilities.
Manufacturers can adjust the properties of golf balls by varying the construction of golf ball intermediate and cover layers. These layers have conventionally been formed by compression or injection molding various polymer materials, such as ionomers and polyurethanes of varying hardness and flexural modulus. Injection and compression molding have practical limitations on layer thickness. It remains a challenge to mold a layer having a thickness of less than about 0.03 inches. In addition, once layers become very thin uniformity problems arise. Other types of molding, such as casting and reaction injection molding (“RIM”) also have limitations. Casting processes generally have undesirable waste, and RIM mold parts are difficult to position to achieve a uniform layer and may leave pin marks on the cores or golf ball subassemblies. Thin layers may also be sprayed on the golf ball assemblies; however, spray applicators or nozzles can be clogged and the liquid compositions to be sprayed may also have undesirably high volatile organic components (VOC).
Other methods used to apply layers to a golf ball utilize electrostatic application of a powder coating to golf ball cores or subassemblies. These types of applications, however, require an electrostatic precursor coating, i.e. RansPrep™ available from Chemical Technology Co., to create a conductive environment on the cores or subassemblies for the powder coating to attach. In addition, complex holding fixtures are required to hold the golf ball subassemblies. The precursor coating is an additional processing step. The holding fixtures are complex because the fixture as a whole should not be conductive, but should be conductive at the holding points. Also, the fixtures typically leave “pick marks” on the cores or subassemblies. Furthermore, powder application of the cores or subassemblies requires additional high temperature heating, i.e. infrared heating, to cure or to melt the powder into a smooth coating.
Therefore, the need remains for methods to apply thin uniform layers to golf balls without the need for additional coatings or complicated fixtures.